On Sun, 23 Dec 2007, Iljitsch van Beijnum wrote:
On 22 dec 2007, at 21:23, Ross Vandegrift wrote:
IPv6 documents seem to assume
that because auto-discovery on a LAN uses a /64, you always have to
use a /64 global-scope subnet. I don't see any technical issues that
require this though. ICMPv6 is capable of passing info on prefixes of
any length - prefix length is a plain old 8bit field.
In fact, until I read the ARIN documents to receive an assignment at
work, I assumed this would be how people would operate. So what's the
concern? Give all end users a /64 and let them subnet that as they
see fit. If DHCPv6 would take care of it automatically with shorter
prefixes, that's fine
First of all, there's RFC 3513:
For all unicast addresses, except those that start with binary value 000,
Interface IDs are required to be 64 bits long and to be constructed in
Modified EUI-64 format.
Second, we currently have two mechanisms to configure IPv6 hosts with an
address: router advertisements and DHCPv6. The former has been implemented in
ALL IPv6 stacks but doesn't work if your subnet isn't a /64. The latter is (I
think) available on the client side in Windows Vista. There are a few DHCPv6
server implementations, but the ones I tested 2 years ago wouldn't do address
assignment. (You still need the router advertisements to learn your default
gateway and prefix length as DHCPv6 can't tell you those.) So although many
people want to stick to the DHCP model they know from IPv4, that's extremely
hard to do with IPv6 the way things currently are.
Actually we tested DHCv6 implementation 2-3 years ago.
http://www.6net.org/publications/deliverables/D3.2.3v3.pdf
The dibbler seemed to be rather complete DHCPv6 implementation. I think
default gateway and prefix length distribution via DHCPv6 will be quite
problematical any many situation. There plenty of organisation who has a
dedicated team/person for network management (routers, switches etc.),
while another team/person for system management (dhcp, servers etc.). So
configuring DHCPv6 requires cooperation which takes time, but users are
complaining....
Best Regards,
Janos Mohacsi